Electrode



July 16, 1940. F C, ELLIS 2,208,023

ELEcToDE Filed Aug. 21. 1937 1i J4 nu i I J5 14 14 il LZ f L. 24 i i6 i il I6 il .E' AJ6 36 J6 @E J ryde afzc @i @7m/m@ @si Patented July 16, 1940v UNITED STATES PATENT ortica 2,208,023 ELECTRODE Francis c. Euis, chicago, m.

Application August 271,

2 Claims.

The present invention relates to an electrode for conveying a current owing through or adjacent a given surface.

In many electrical processes it is necessary to apply an electrode to a surface for the purpose of passing an electric current between said surface and the electrode as, for example, when it is desired to measure or ascertain the properties of the said current.

In particular when employing devices, such as the electro-cardiograph or other electrical diagnostic device, it is necessary to make a contact between the surface ofthe body and an electrode in order to determine the characteristics of the existing electrical eect. As long as the pressure with which the electrode is applied to the surface is maintained constant, the-current flowing between the electrode and the surface will remain uniform, other factors being constant. A variation, however, inthe contact pressure may tend to aiect the current ow by increasing or decreasing the resistance atthe point of contact and it is accordingly necessary to exert special care to maintain a constant contact pressure on more fully appear during the course and progress.

of the following specification.

Referring to the drawing:

Figure 1 is a perspective view of an electrode constructed in accordance with the present invention. l

Figure 2 is a sectional elevation taken on the line 2-2 in Figure 1.

Figure 3 is an alternative form of an electrode constructed in accordance with the present invention.

Figure 4 is a sectional view taken on the line' 4 4 in Figure 3.

'I'he illustrative embodiment disclosed in Figure 1, comprises a cylindrical handle portion I of suitable insulating material, such as Bakelite, which Vis provided interiorly and axiallyv thereof with a tubular insert I2 which may comprise any other suitable tube, preferably of metal.l

1937, Serial No. 160,283

Vviewed in Figure 1, is secured a sleeve I4 also of insulating material which is rigidly secured to the handle portion in any desired manner. The lower edge of the sleeve I4 is provided with an inwardly extending annular lip I6 for a purpose which will hereinafter be described more in detail.

The electrode proper or conducting member I 8 is of cylindrical shape and has secured about the upper end thereof a cylindrical sleeve 20 which engages into the inner cylindrical bore of the sleeve I4 and provides a bearing surface therewith of considerable extent so that the contact member. I8 may bereciprocated axially of the handle and sleeve but will always be maintained in position extending longitudinally of the axis of the sleeve. The shoulder 22 formed by the lower end of the sleeve 20, moreover, engages with the inner side of the annular, inwardly extending lip I 6, providing a stop for limiting movement of the conducting member I8 with respect to the sleeve, while a compression spring 24 serves to maintain the electrode normally in said limiting position.

Further means is provided to guide and position the conducting member I8 and comprises a cylindrical rod 26 of some suitable conducting material of the proper diameter to engage slidably within the tubular insert I2. Electrical contact with the conducting member I8 is made through the agency of a standard cord tip connector 28 threaded into the upper end of the handle, as viewed in Figure l, and having soldered to the lower portion thereof a flexible wire 30. This wire extends loosely through the interior space formed by the tubular insert I2 and connects with the cylindrical rod 26 through the agency of a set screw 32.

In use, the electrode i's connected with the electrical device in conjunction with which it is intended to be employed through the agency of any suitable electrical conduit having its end inserted into and making contact with the cord tip connector 28. The handle portion I Il may then be grasped manually and the conducting member I8 presented iiatwise against the surface to be measured with suilcient force so that the annular lip portion I6 of the sleeve is brought against the surface. VRegardless of how much additional force is applied through the handle I0, the electrode cannot be moved forwardly any further-into contact with the surface since movement is limited by the said annular lip I 6.

Meanwhile, however, the conducting member I8 will have been forced into the sleeve against the resilient action of the spring 24 until its outer surface is substantially in the same plane with the end of the sleeve I4' in which position the -compression spring 24 will always exertl a constant pressure thereagainst. If ait is desired to break the contact with the surface and again remake it at some later time or` at some different position, the conducting member I8 will always be retracted to the same relative position when the electrode is firmly pressed against the surface in the manner hereinbefore mentioned, with the result that the contact pressure, duringtexgh time of use, will remain substantially the samf' As a result, the electrical current flowing through the circuit comprising the surface to be measured, the conducting member I8, the conducting lrod 28 and the wire 30, the cord tip connector 28 the edge of the sleeve I4 may tend to sink if of only inconsiderable extent. Thus, in applying the outer face of the conducting member I8 to the surface of the body, the device is always accurately positioned by the surface 36 so that the area contacted by the surfaces of the conducting member I8 will be contacted with the same force at all times.

The conducting member I8 shown inFigures 3 -and 4, is provided with an annular shoulder 38 which, in conjunction with the annular lip I6, limits the voutward, movement thereof. According to this ,embodiment there is provided a plurality of spaced conducting members since the electrode proper, as indicated by the numeral I8, is split into a right and left section, 40 and 42, respectively, as viewed in Figure 3. 'I'hese two sections p the handle.

are separated and electrically insulated from one another by theA interposed layer of non-conducting material 44. 4 i The structure is preferably generally cylindrical in shape and the two conducting portions 4I) and 42 and the insulating barrier 44 may be cemented together or formed into a unitary unit by any suitable means. As in the previously described embodiment, the conducting rod 26 extends into the tubular insert I2 lto position the conducting member for slidable movement with respect to A double cord tip connector 46 is mounted on the end of the electrode and has conducting portions 48 adapted to make electrical contact with the cord tips on the conduits of the instrument with which' the present invention is to be employed. Flexible insulated wires 50 con nected at their upper ends respectively to the cord tip connector extend interiorly of the device through the tubular insert I2'and are secured to the respective conducting portions 40 and 42 of the conducting rod 26 by means of set screws 32.

This embodiment is of particular utility where v"fr example, and if desired may comprise in the same unit dissimilar metals, in the event it is desired to measure an electrolytic effect.

It is thought that the invention and numerous of' its attendant advantages will be understood from the foregoing description and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein described being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. In a contacting device for making electrical contact with a surface of a body or the like comprising an electrode support lhaving a manual control handle Afor facilitating application to said surface, said contacting device comprising a relatively rigid, gauging surface arranged in a predetermined relatively flat plane, an electrode arranged generally centrally of lsaid surface and ^having a conducting contact surface associated therewith, said electrode being movable to positions laterally on either side vof said plane, and resilient'means for applying a constant force to said conducting surface when the two surfaces are substantially co-planar, said conducting contact surface'compriing two separate sections of dissimilar materials and having an insulating partition therebetween.

2. In a contacting device for making electrical contact with a surface of a body or the like comprising an electrode support having a manual control handle for facilitating application to said surface,said contacting device comprising a relatively rigid, gauging member arranged in a predetermined relatively ilat plane, an electrode arranged generally centrally of said member and having` a conducting contact surface associated therewith, said electrode being movable to positions laterally on either side of said plane, and

means for applying a constant force to said con- 

